`gj#dZddlmZddlZddlZddlZddlZddlZddlZddl Z dZ dZ ejfd dZ d dZd dZddd Zed k(rej$eyy)uParent-death watchdog supervisor for stdio MCP subprocesses. Problem this fixes (#TBD): a stdio MCP server (e.g. ``npx -y mcp-remote ``) is spawned as a direct child of the Hermes process. Hermes's own teardown path (``MCPServerTask.shutdown()`` / ``_kill_orphaned_mcp_children`` at final exit) reaps it cleanly on a *graceful* exit. But if the spawning Hermes process dies hard — ``kill -9``, an OS-level crash, a force-quit of the TUI/desktop app — that teardown code never runs, and the child (plus any of its own descendants, e.g. mcp-remote's spawned ``node`` process) is orphaned. macOS has no direct equivalent of Linux's ``prctl(PR_SET_PDEATHSIG)`` to make the kernel auto-kill a child when its parent dies, so nothing reaps these until the next Hermes startup's opt-in ``_kill_orphaned_mcp_children()`` sweep — which only runs if something calls it. Repeated ungraceful session restarts can pile up N orphaned processes, all racing to hold the same upstream SSE session, producing errors like "Invalid request parameters" / "Received request before initialization was complete" on the *legitimate* new connection. Fix: don't spawn the MCP server command directly. Spawn this supervisor instead, which: 1. execs the real command as its own child (own process group via ``start_new_session``, so it doesn't inherit the supervisor's controlling terminal weirdly and so we can killpg it cleanly); 2. transparently passes stdin/stdout/stderr through — the MCP stdio protocol talks directly over those pipes, so the supervisor must be a no-op relay, not a bytes-in-the-middle proxy; 3. runs a background thread that polls the direct POSIX parent identity: compare current ``getppid()`` against the parent PID recorded when the wrapper was created; 4. the instant the original parent is gone, terminates the real child's process group (SIGTERM, grace period, then SIGKILL) and exits. This is intentionally a thin, standard-library-only script so it starts fast and can't itself become a resource leak. Usage (see ``tools/mcp_tool.py::_run_stdio``):: python3 -m tools.mcp_stdio_watchdog \ --ppid -- ... ) annotationsNg@g@c||k7S)zDReturn whether this process no longer has its original POSIX parent.) original_ppidgetppids K/root/.hermes/venv/lib/python3.12/site-packages/tools/mcp_stdio_watchdog.py _is_orphanedr 9s 9 %%cZttdd}|( |j|jty tj|j}ttdtj}tj|fD]$} ||| |jtyy#t t jf$r|jYywxYw#tt f$rYywxYw#ttt f$rYywxYw#t j$rYwxYw)aKBest-effort SIGTERM-then-SIGKILL of the child's process group. This module only ever runs on POSIX (the wrap site in tools/mcp_tool.py gates on ``os.name == "posix"``), but guard the POSIX-only primitives anyway so an accidental Windows import/execute degrades to a plain child kill instead of AttributeError. killpgN)timeoutSIGKILL)getattros terminatewait _TERM_GRACE_SOSError subprocessTimeoutExpiredkillgetpgidpidProcessLookupErrorsignalSIGTERMPermissionError)procr pgidsigkillsigs r_terminate_process_groupr">sR4 (F ~  NN  IImI , zz$((#fi8G(   4   IImI ,  223  IIK   ( #OW=    ((   sF&B5C$ C9D5)C! C!$C65C69DDD*)D*c|jBt|r t|ytjt |jAyyN)pollr r"timesleep_POLL_INTERVAL_S)rrs r_watchdog_loopr)_s< ))+   & $T *  #$ ))+ r c0tjd}|jdtd|jdtj|j |}t |j}|r |dd k(r|d d}|std tj y tj|tjtjtjdfd}tjtj |tjtj"|t%j&t(|j*fd}|j- j/S#t0$rt3YywxYw)Nz1Parent-death watchdog for a stdio MCP subprocess.) descriptionz--ppidT)typerequiredcommand)nargsrz--z/mcp_stdio_watchdog: no command given after '--')file)stdinstdoutstderrstart_new_sessioncLttjd|zy)N)r"sysexit)signumframers r_forward_shutdownzmain.._forward_shutdowns & vr )targetargsdaemon)argparseArgumentParser add_argumentint REMAINDER parse_argslistr.printr9r5rPopenr3r4rrSIGINT threadingThreadr)ppidstartrKeyboardInterruptr")argvparserr? real_argvr=watchdogrs @rmainrUgsE  $ $GF sT:  ););<   T "DT\\"IYq\T)abM  ?cjjQ   iizzzz  D MM&.."34 MM&--!23DII H  NNyy{  &s.E>>FF__main__)rrEreturnbool)rsubprocess.PopenrWNone)rrYrrErWrZr$)rQzlist[str] | NonerWrE)__doc__ __future__rrBrrrr9rLr&r(rrr r"r)rU__name__r:rr rr^sn'R#    .0ZZ& B%2j z CHHTVr